Make sure that remote shares use the correct uid casing

apps/files_sharing/api/server2server.php

@@ -53,6 +53,7 @@ class Server2Server {
 				return new \OC_OCS_Result(null, 400, 'The mountpoint name contains invalid characters.');
 			}
 
+			// FIXME this should be a method in the user management instead
 			\OCP\Util::writeLog('files_sharing', 'shareWith before, ' . $shareWith, \OCP\Util::DEBUG);
 			\OCP\Util::emitHook(
 				'\OCA\Files_Sharing\API\Server2Server',

lib/base.php

@@ -608,6 +608,14 @@ class OC {
 		OC_User::useBackend(new OC_User_Database());
 		OC_Group::useBackend(new OC_Group_Database());
 
+		// Subscribe to the hook
+		\OCP\Util::connectHook(
+			'\OCA\Files_Sharing\API\Server2Server',
+			'preLoginNameUsedAsUserName',
+			'\OC_User_Database',
+			'preLoginNameUsedAsUserName'
+		);
+
 		//setup extra user backends
 		if (!self::checkUpgrade(false)) {
 			OC_User::setupBackends();

lib/private/user/database.php

@@ -294,6 +294,20 @@ class OC_User_Database extends OC_User_Backend implements \OCP\IUserBackend {
 		return $result->fetchOne();
 	}
 
+	/**
+	 * returns the username for the given login name in the correct casing
+	 *
+	 * @param string $loginName
+	 * @return string|false
+	 */
+	public function loginName2UserName($loginName) {
+		if ($this->userExists($loginName)) {
+			return $this->cache[$loginName]['uid'];
+		}
+
+		return false;
+	}
+
 	/**
 	 * Backend name to be shown in user management
 	 * @return string the name of the backend to be shown
@@ -302,4 +316,22 @@ class OC_User_Database extends OC_User_Backend implements \OCP\IUserBackend {
 		return 'Database';
 	}
 
+	public static function preLoginNameUsedAsUserName($param) {
+		if(!isset($param['uid'])) {
+			throw new \Exception('key uid is expected to be set in $param');
+		}
+
+		$backends = \OC::$server->getUserManager()->getBackends();
+		foreach ($backends as $backend) {
+			if ($backend instanceof \OC_User_Database) {
+				/** @var \OC_User_Database $backend */
+				$uid = $backend->loginName2UserName($param['uid']);
+				if ($uid !== false) {
+					$param['uid'] = $uid;
+					return;
+				}
+			}
+		}
+
+	}
 }